Reland: URLRequestJob: change ReadRawData contract

This CL is to reland crrev.com/1410643007 which was
reverted in crrev.com/1437523002.

Previously, the interface for URLRequestJob::ReadRawData was as follows:

  bool ReadRawData(IOBuffer*, int, int*)

Subclasses were expected to signal completion of the ReadRawData call by
calling NotifyDone, SetStatus, or maybe one of the other Notify* functions
on URLRequestJob, most of which do internal housekeeping and also drive the
URLRequest's state machine. This made it difficult to reason about the
URLRequestJob's state machine and needlessly complicated most of URLRequestJob.

The new interface is as follows:

  int ReadRawData(IOBuffer*, int)

Subclasses are required to either:

a) Return ERR_IO_PENDING, and call ReadRawDataComplete when the read completes in any way, or
b) Return a count of bytes read >= 0, indicating synchronous success, or
c) Return another error code < 0, indicating synchronous failure.

This substantially narrows the interface between URLRequestJob and its
subclasses and moves the logic for the URLRequest state machine largely into
URLRequestJob.

Also, the signature of URLRequestJob::ReadFilteredData and some other internal
URLRequestJob helpers changes to propagate detailed error codes instead of
coercing all errors to FAILED.

TBR=michaeln@chromium.org,mtomasz@chromium.org,jianli@chromium.org,zork@chromium.org

BUG=474859
BUG=329902

Review URL: https://codereview.chromium.org/1439953006

Cr-Commit-Position: refs/heads/master@{#360327}

2 files changed, 4 insertions, 12 deletions

diff --git a/content/browser/appcache/appcache_url_request_job.cc b/content/browser/appcache/appcache_url_request_job.cc
index 82997f7..de924a1 100644
--- a/content/browser/appcache/appcache_url_request_job.cc
+++ b/content/browser/appcache/appcache_url_request_job.cc
@@ -341,7 +341,6 @@ void AppCacheURLRequestJob::SetupRangeResponse() {
 void AppCacheURLRequestJob::OnReadComplete(int result) {
   DCHECK(is_delivering_appcache_response());
   if (result == 0) {
-    NotifyDone(net::URLRequestStatus());
     AppCacheHistograms::CountResponseRetrieval(
         true, is_main_resource_, manifest_url_.GetOrigin());
   } else if (result < 0) {
@@ -349,13 +348,10 @@ void AppCacheURLRequestJob::OnReadComplete(int result) {
       storage_->service()->CheckAppCacheResponse(manifest_url_, cache_id_,
                                                  entry_.response_id());
     }
-    NotifyDone(net::URLRequestStatus(net::URLRequestStatus::FAILED, result));
     AppCacheHistograms::CountResponseRetrieval(
         false, is_main_resource_, manifest_url_.GetOrigin());
-  } else {
-    SetStatus(net::URLRequestStatus());  // Clear the IO_PENDING status
   }
-  NotifyReadComplete(result);
+  ReadRawDataComplete(result);
 }
 
 // net::URLRequestJob overrides ------------------------------------------------
@@ -424,18 +420,14 @@ int AppCacheURLRequestJob::GetResponseCode() const {
   return http_info()->headers->response_code();
 }
 
-bool AppCacheURLRequestJob::ReadRawData(net::IOBuffer* buf,
-                                        int buf_size,
-                                        int* bytes_read) {
+int AppCacheURLRequestJob::ReadRawData(net::IOBuffer* buf, int buf_size) {
   DCHECK(is_delivering_appcache_response());
   DCHECK_NE(buf_size, 0);
-  DCHECK(bytes_read);
   DCHECK(!reader_->IsReadPending());
   reader_->ReadData(buf, buf_size,
                     base::Bind(&AppCacheURLRequestJob::OnReadComplete,
                                base::Unretained(this)));
-  SetStatus(net::URLRequestStatus(net::URLRequestStatus::IO_PENDING, 0));
-  return false;
+  return net::ERR_IO_PENDING;
 }
 
 void AppCacheURLRequestJob::SetExtraRequestHeaders(
diff --git a/content/browser/appcache/appcache_url_request_job.h b/content/browser/appcache/appcache_url_request_job.h
index 95a3e18..8f51e7b 100644
--- a/content/browser/appcache/appcache_url_request_job.h
+++ b/content/browser/appcache/appcache_url_request_job.h
@@ -148,7 +148,7 @@ class CONTENT_EXPORT AppCacheURLRequestJob
   net::LoadState GetLoadState() const override;
   bool GetCharset(std::string* charset) override;
   void GetResponseInfo(net::HttpResponseInfo* info) override;
-  bool ReadRawData(net::IOBuffer* buf, int buf_size, int* bytes_read) override;
+  int ReadRawData(net::IOBuffer* buf, int buf_size) override;
 
   // Sets extra request headers for Job types that support request headers.
   // This is how we get informed of range-requests.